The 21-year-old Gloucester flanker is among four new caps named by Wales head coach Warren Gatland, with wing Eli Walker, centre Tyler Morgan and lock Dominic Day also being handed starts.

St Helens-born Moriarty, whose father Paul and uncle Richard both played for Wales, helped England win successive Under-20 World Cup finals in 2013 - against Wales - when his team-mates included current senior England stars Anthony Watson and Jack Nowell, and 2014.

Moriarty is not tied to England because he has not represented either the senior team or England's designated second XV, the Saxons.

There are two more uncapped players on the replacements' bench in New Zealand-born fly-half Gareth Anscombe, whose mother is from Cardiff, and Anscombe's Cardiff Blues colleague, hooker Kristian Dacey.

The team will be captained by Scarlets centre Scott Williams, who leads his country for the first time.

Saturday's sell-out clash is the first of three warm-up games on Wales' schedule. It will be followed by a return fixture against Ireland in Dublin on August 29, then Italy visiting Cardiff seven days later.

Wales' opening World Cup pool fixture is against Uruguay at the Millennium Stadium on September 20, with their group also comprising England, Australia and Fiji.

Elsewhere in the line-up, there is only a second Test start at fly-half for Gloucester's James Hook since the 2011 World Cup, although his half-back partnership with Mike Phillips boasts a combined total of 170 caps.

Wales head coach Warren Gatland's starting XV largely comprises players pushing for what are thought to be just a few remaining places in his final 31-man World Cup squad, which will be announced later this month.

The uncapped quartet have golden chances against Ireland to press their claims, along with the likes of full-back Hallam Amos, prop Nicky Smith and number eight Dan Baker, who packs down in the back-row alongside Moriarty and Justin Tipuric.

"Saturday is a real opportunity for these players to put their hand up," said Gatland, whose players will return to competitive action following intensive training camps in Switzerland and Qatar.

"We have been really impressed over the last few weeks. We have put the players under a lot of pressure, and they have responded really well.

"This is their opportunity to show what they can do on the international stage.

"We have the right blend of youth and experience, and it's all about grasping the chance at this level.

"It's going to be a huge occasion - Ireland coming to town, a packed Millennium Stadium and players with everything to play for."